Manganiferous Soils in Maryland: Regional Extent and Field-Scale Electromagnetic Induction Survey
- Rebecca R. Bourgault *a and
- Martin C. Rabenhorstb
There are some unique soils in central Maryland with extremely high quantities of Mn and Fe oxides, up to 141 g kg−1 Mn and 169 g kg−1 Fe (extracted by dithionite–citrate–bicarbonate). Such high quantities of Mn oxides have pigmented the entire soil matrix black in subsoil horizons. Previously, little was known about the extent of these manganiferous soils in Maryland. Pedons were observed in transects across several fields containing manganiferous soils to better understand their spatial variability and possible relationship to landscape and geology. Manganiferous soils are heterogeneous; some pedons show modest to moderate Mn enrichment in the form of black nodules or coatings, while other pedons show extreme Mn enrichment in the form of black, loamy material up to 8.5 m deep. The soils seem to occur in relation to areas mapped as having marble bedrock in the geologic survey. The utility of electromagnetic induction (EMI) for delineating manganiferous soil units was tested for the first time. Apparent electrical conductivity (ECa) readings from the EM38DD EMI sensor had a significant empirical relationship to Mn content of the studied soils (R2 = 0.88), so maps generated from ECa data correspond reasonably well to observations made during transect work. Electromagnetic induction is therefore a useful tool for delineating manganiferous soils, which occurred in units of approximately 1 to 2 ha in each of the three fields observed.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2012. . Copyright © by the Soil Science Society of America, Inc.